Just because you disagree with a view doesn't mean you have to criticize the person Payne.
As for the relative good and evil, yes, it does mean that it cannot be defined, because if you accept the relative meaning of good and evil, then you accept that they can mean two completely opposite things. With that being said, one word cannot have opposite meanings, it takes away any actual meaning the word once held (if at all).
Your second part about how only ignorant or psychotic people view evil things as good, I'd like to point out that many of the world powers are considered good in their own light, yet evil by those they try to control. Which is right? Who is psychotic?
The best example would probably be America going to war with other countries. The citizens view their country as helpful, peace loving, and all around good; meanwhile, those being attacked view America as evil, along with a good number of people who think America is downright retarded for claiming to go there for peace, or any number of other reasons. Would that make America psychotic or ignorant?
There are grey areas no matter which situation you look at, and it's because of those grey areas, and our ability to add new variables into the situation, that good and evil cannot be defined.